Over 40,000 fans signed a petition in support of the show, which was presented by Sir Patrick Moore until his death last December. Photograph: Roger Bamber/Rex Features

The sun will not set on the The Sky at Night after the BBC announced the long-running science show would move to a new slot on BBC4 following a petition signed by 40,000 viewers who feared it would be axed.

The astronomy show, first broadcast in 1957, will lose its slot on BBC1 but will be expanded from 20 to 30 minutes in its new monthly home on BBC4, with a repeat on BBC2.

More than 40,000 fans signed an online petition in support of the show, which was presented by Sir Patrick Moore until his death last December, aged 89.

The programme will be off air in January, when the gap will be filled by BBC2's live astronomy series, Stargazing Live, presented by Professor Brian Cox and Dara O Briain, before returning in February.

Kim Shillinglaw, head of commissioning science and natural history, said: "Sir Patrick Moore inspired generations of astronomers and I hope that alongside the BBC's other astronomy content, such as BBC2's Stargazing Live, The Sky at Night will enthuse further generations about the wonder of the night sky."

Losing its BBC1 slot is likely to deprive the show of its biggest audiences. The show's last BBC1 outing, on 6 October, was watched by 655,000 viewers. A programme on BBC1 on 4 September, featuring amateur astronomers in their back gardens, was watched by nearly 1.5 million.

The Sky at Night's audiences on BBC4, where it is also currently repeated, are more modest, with one recent edition watched by an average of 317,000 viewers.

No decisions have been made about the presenter's role on the show which has been filled by a series of guest hosts following Moore's death.

The Sky at Night is one of the BBC's longest running TV shows, its longevity eclipsed by current affairs show Panorama, which began four years earlier in 1953.

Moore presented a total of 721 episodes, missing just one outing in the programme's history, when he was struck down by food poisoning.